The present invention relates to transducers. More particularly, the present invention relates to electronic measurement of displacement.
Devices and methods for measuring position and displacement generally are known. Transducers that convert mechanical energy to electrical energy are used in a variety of fields, such as potentiometers, process transmitters, or load cells. One such transducer is a feedback device used in a fuel metering system. A commonly used transducer that converts mechanical position to an electrical signal is a Linear Variable Differential Transformer (LVDT). An LVDT usually includes three inductive coils and a magnetic slug. One of the coils is driven with an electric current, and the position of the slug can be determined based on the induced current through the other two coils. Rotary versions of differential transformers are also known, such as Rotary Variable Differential Transformers (RVDTs).
Position sensing devices such as LVDTs and RVDTs take up space, add weight, and have construction features that can create undesired failure modes and associated high failure rates. Temperature and vibration in the environment in which the LVDTs and RVDTs are used can be damaging to these sensing devices. Additionally, LVDTs and RVDTs employed with actuators contribute significantly to the cost of devices such as fuel metering systems, and for specific applications, are often purchased as special items from a limited number of approved sources.